A need exists for a method for fabricating large arrays of transistors from graphene nanoribbons. With Moore's Law scaling of silicon reaching its limits, new technologies are required to continue making faster, more cost efficient processors. The current semiconductor roadmap has known solutions for achieving milestones six years into the future with looming questions beyond.
One potential silicon replacement is graphene due to its inherently high carrier mobility. However, the lack of a natural band gap in graphene has hindered its development for digital electronics applications. Without a proper band gap, the material is always conductive, even in the OFF state. This can represent an enormous power sink, not practical for commercial electronics. Chemical treatments have been demonstrated to open a small bandgap, but these typically destroy the conduction properties of graphene as well. It has been theorized that graphene nanoribbons (GNRs) having a width of less than ten nanometers would have a band gap of tens of eV due to quantum confinement effects, and there are some experiments which corroborate this picture. However, scalability and reproducibility of GNR fabrication remains an unsolved problem.
While there have been experiments demonstrating that GNR samples can achieve ON/OFF ratios>1000, these samples are very hard to produce, often taking months to make one functional device. Such efforts have used GNRs that were deposited randomly on a substrate from solution, or created in a top down process using electro-migration. More conventional lithographic processing of graphene tends to leave residues behind, which can contaminate the sample, and which can reduce its effectiveness as a transistor. To make a practical commercial technology, scale up must be demonstrated using other means of device fabrication. For graphene to supplant silicon in next generation processors, there must be a way to fabricate large numbers of graphene transistors with high ON/OFF ratios, i.e. having a band gap, reproducibly.
In view of the above, it is an object of the present invention to provide GNR's and methods for fabricating GNR's that can allows for large numbers of graphene nanotransistors with band gaps. Another object of the present invention is to provide GNR's and methods for fabricating GNR's that can result in GNR's with band gaps, but that can also retain their conductivity. Yet another object of the present invention can be to provide GNR's and methods for fabricating GNR's that can fabricate an orderly array of GNR's using a bottom up, vice a top down process. Still another object of the present invention can be to provide methods for GNR's and methods for fabricating GNR's that can be consistent and reproducible. Still another object of the present invention can be to provide GNR's and methods for fabricating GNR's that can be scalable and that can be practiced in a cost-efficient manner.